vm

[filip-parity]

Existing zkVm available here as example for grooming this task:

/// Enables/Disables use ZK-VM for transact/call and create instructions.
function zkVm(bool enable) external pure;

---

Proposed Cheat Code for PVM

• Function Name: pvmEnable
• Signature:

function pvmEnable(bool enable) external pure;

• Purpose: Enables or disables the PVM context for transact, call, and create instructions (TBD if more), allowing switching between PVM and EVM or other contexts during testing.
• Parameters:
  • enable: Boolean to toggle PVM context (true for PVM, false for EVM or default context).
• Example Usage:

// Contract to be deployed in different contexts
vmExt.pvmEnable(true);
new PolkaContract(1); // Deployed in PVM
new PolkaContract(2); // Deployed in PVM
vmExt.pvmEnable(false);
new PolkaContract(3); // Deployed in EVM
new PolkaContract(4); // Deployed in EVM

---

Please decide how to handle enabling pvm/evm as the pallet-revive support both VMs

Estimation: 10D

[filip-parity]

Tentative Changes Needed

1. Add PVM Group to Cheat Code Groups
   File: polkadot-foundry/crates/cheatcodes/spec/src/cheatcode.rs
2. Update Group Safety Mapping
   File: polkadot-foundry/crates/cheatcodes/spec/src/cheatcode.rs
3. Add PVM Enable Cheat Code Definition
   File: polkadot-foundry/crates/cheatcodes/spec/src/vm.rs
4. Create PVM Module
   File: polkadot-foundry/crates/cheatcodes/src/pvm.rs (new file)
5. Add PVM Module to lib.rs
   File: polkadot-foundry/crates/cheatcodes/src/lib.rs
6. Update Cheatcodes Struct Registration
   File: polkadot-foundry/crates/cheatcodes/spec/src/lib.rs
7. Add PVM State Storage
   File: polkadot-foundry/crates/cheatcodes/src/inspector.rs
8. Update Cheatcodes Initialization
   File: polkadot-foundry/crates/cheatcodes/src/inspector.rs
9. Add PVM Documentation
   File: polkadot-foundry/docs/dev/cheatcodes.md
10. Update Test Files
    File: polkadot-foundry/testdata/cheats/Vm.sol
11. Add Integration Tests
    File: polkadot-foundry/crates/cheatcodes/src/pvm.rs
    12, Update EVM Context Handling
    File: polkadot-foundry/crates/cheatcodes/src/evm.rs
12. Add PVM Context Switching Logic
    File: polkadot-foundry/crates/cheatcodes/src/inspector.rs
13. Update Transaction Execution Flow
    File: polkadot-foundry/crates/evm/core/src/executor.rs
14. Add PVM Context Validation
    File: polkadot-foundry/crates/cheatcodes/src/pvm.rs

[smiasojed]

Could we please mark this ticket as optional in the title? It will be needed when we have dual EVM and PVM support

[pkhry]

Possible approaches at implementing this in foundry

Approach 1 (different cheatcodes for different VM's)

Instead of equivalent for vm.zkVm - use vm.reviveEvm and vm.pVm.

Potential issues:

• 1. Disabling selected vm after enabling the other one. you can flip calls to vm.pVm/vm.reviveEvm places and the issue will be the same:

vm.pVm(true); 
...
vm.reviveEvm(true);
...
// calls to `vm.pVm(false)` should be trapped failure must be returned.

• 2. Contexts should be stacked or not?

vm.pVm(true); 
...
vm.reviveEvm(true);
...
vm.reviveEvm(false); // or vm.VmSkip()

Should we use pvm context for the code following the last call or should we completely return to foundry's evm context?

• 3. Will have increased complexity because of the things described above due to the need to juggle states and contexts around.

Approach 2 (same cheatcode).

instead of equivalent for vm.zkVm use vm.reviveVm(bool enable, kind uint256)
where

• kind = 0 -> pvm
• kind = 1 -> embedded Evm

Pros:

• no need to juggle between multiple contexts
• simpler to implement and extend

Other things

• Do we want to support execution on both vm's (reviveEvm and pvm) at the same time to make sure that the storage changes are equivalent?

[filip-parity]

FYI as part of issues/202 I think (not 110% sure yet) I am going to try to add the following block to be able to test things accordingly under crates/cheatcodes/spec/src/vm.rs:

/// Enables or disables PVM (PolkaVM) mode for contract execution.
/// When enabled, contracts will be executed using the PVM runtime instead of EVM.
/// Example usage:
/// vm.pvm(true);  // Enable PVM mode
/// vm.pvm(false); // Disable PVM mode (use EVM)
#[cheatcode(group = Utilities)]
function pvm(bool enabled) external;

[pkhry]

FYI as part of issues/202 I think (not 110% sure yet) I am going to try to add the following block to be able to test things accordingly under crates/cheatcodes/spec/src/vm.rs:

/// Enables or disables PVM (PolkaVM) mode for contract execution.
/// When enabled, contracts will be executed using the PVM runtime instead of EVM.
/// Example usage:
/// vm.pvm(true); // Enable PVM mode
/// vm.pvm(false); // Disable PVM mode (use EVM)
#[cheatcode(group = Utilities)]
function pvm(bool enabled) external;

not much point as without the mock_runtime its still not possible to test anything